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CHANGES IN HEART RATE VARIABILITY AND LUNG FUNCTION OBSERVED IN NC PATROL TROOPERS EXPOSED TO PM AND AIR TOXICS
Citation:
Riediker, M, W. E. Cascio, T. R. Griggs, M. C. Herbst, R B. Devlin, R W. Williams, S. McCorquodale, AND P A. Bromberg. CHANGES IN HEART RATE VARIABILITY AND LUNG FUNCTION OBSERVED IN NC PATROL TROOPERS EXPOSED TO PM AND AIR TOXICS. Presented at American Heart Assoc. 75th Scientific Session, Chicago, IL, November 17-20, 2002.
Description:
Changes in Heart Rate Variability and Lung Function in NC Patrol Troopers exposed to PM and Air Toxics
Michael Riediker1, Wayne E Cascio1, Robert B Devlin2, Thomas Griggs1&4, Margaret Herbst1, Ronald W Williams3, Steve P McCorquodale4, Philip A Bromberg1
1) University of North Carolina at Chapel Hill, NC
2) U.S. EPA, NHEERL, RTP, NC
3) U.S. EPA, NERL, RTP, NC
4) North Carolina State Highway Patrol, Raleigh, NC
Cars are a major source of air pollution. Individuals whose jobs involve being on the road may be exposed to high concentrations from vehicle emissions. This exposure might alter cardiac and pulmonary function, induce inflammation and change concentrations of vasoactive mediators in the plasma.
Ten healthy non-smoking male NC highway patrol troopers were monitored during 25 late-shift-workdays (3-12pm), resulting in data for 50 person-days. The patrol cars were equipped with monitors for temperature, relative humidity, PM2.5, CO, NO2, polycyclic aromatic hydrocarbons, ozone and volatile organics. Spirometry was done before and after the shift, blood drawn in the afternoon, and heart rate variability measured during the shift and the following night. In addition activities and route of the patrol car were recorded.
Variation of pollutant levels was large. The daily mean PM2.5 concentration was 24 ug/m3 (range 4 to 54 ug/m3). End-of-shift lung function parameters decreased on average compared to the before-shift values: FVC (-50.5 ml or -0.68%, n.s.), FEV1 (-90.3 ml or -1.88%, p=0.02), FEF25-75 (-199.1 ml/s or -3.81%, p=0.002). Most heart rate variability parameters changed strongly: Mean R-R interval changed from 827 ms before shift to 955 ms (p<0.0001) after shift, SDNN from 66 ms to 83 ms (p=0.0009), PNN50 from 19.7% to 37.6% (p<0.0001), LFP from 10.0 to 8.3 (n.s.), nLFP from 0.74 to 0.63 (p<0.0001), HFP from 3.4 to 4.6 (p=0.04), nHFP from 0.26 to 0.37 (p<0.0001), and the ratio of LF/HF from 3.6 to 2.0 (p<0.0001). Significances paired t-test.
The results suggest a significant effect of an in-vehicle patrol-like work shift on heart rate variability and forced expiratory flow rates. The changes in heart rate variability indicate increased parasympathetic and decreased sympathetic activity at the end of the shift. Reduced airways conductance would be consistent with a shift in the sympatho-vagal balance. We are now determining whether the differences observed are associated with exposure to air pollutants or possibly due to other work-related factors such as fatigue and stress, or diurnal variation. (This abstract does not necessarily reflect EPA policy)